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61.
阐述了SiGe器件的主要研究方向以及国内外对SiGe材料和器件的研究情况,并对SiGe器件与Si器件和GaAs器件的发展前景进行了比较。 相似文献
62.
1IntroductionInthetraditionalconceptsofscanningelectronmicroscopy,itisusualythoughtthatsecondaryelectronsaresensitivetorugg... 相似文献
63.
《International Journal of Hydrogen Energy》2020,45(1):149-159
Ag3PO4 was deposited on TiO2 by in-situ precipitation to fabricate Ag3PO4–TiO2 heterojunction with different ratios of Ag3PO4. The electronic band structures of TiO2 and Ag3PO4 were determined by means of ultraviolet photoelectron spectroscopy and UV–visible spectrometry. The Fermi levels of TiO2 and Ag3PO4 were calculated to be −5.09 eV and −5.95 eV, respectively, and accordingly the energy band diagrams were constructed. The hydrogen production rates of bare TiO2 and Ag3PO4–TiO2 heterojunctions were measured under 300 W Xe lamp with a solar filter (AM 1.5). The heterojunction formed with 12 wt% Ag3PO4 showed the highest hydrogen evolution rate (44.5 μmol g−1h−1) which is 5.7 times higher than that of TiO2. When Au nanoparticles were deposited on this heterojunction, it resulted in 10.2 times (453.0 μmol g−1h−1) further improvement of hydrogen generation. The hydrogen evolution performance is consistent with the result of photoluminescence analysis. 相似文献
64.
Longzhu Li Changhai Liu Yangyang Qiu Naotoshi Mitsuzak Zhidong Chen 《International Journal of Hydrogen Energy》2017,42(31):19654-19663
Morphology controlling and surface modification of semiconductors is the key for efficient photoelectrochemical (PEC) water splitting systems. This work provides a new strategy for achieving morphology control and heterojunction construction simultaneously by one-step hydrothermal method. The α-Fe2O3/CQDs heterojunction photoanode with convex-nanorods morphology is successfully prepared by hydrothermal method in CQDs (Carbon Quantum Dots) aqueous contained iron precursor followed by low temperature annealing treatment. Compared with bare hematite photoanode, the α-Fe2O3/CQDs photoanode has 8.5 time higher photocurrent density (at 1.23 V vs. RHE) of 0.35 mA cm?2 and a negative shift of onset potential about 300 mV. The enhanced photoelectrochemical response is attributed to the convex-nanorods which benefit higher absorbance of light and the formed α-Fe2O3/CQDs heterojunction, which can efficiently enhance the electron-hole separation and reduce the surface charge recombination. The morphology and properties of the sample were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fouriertrans form infrared spectroscopy (FTIR), UV–vis spectra, X-ray diffractometry (XRD), X-ray photoelectron spectra (XPS), and photoelectrical measurements. 相似文献
65.
《International Journal of Hydrogen Energy》2020,45(33):16550-16559
In order to enhance the photoelectrochemical (PEC) performance of tungsten oxide (WO3), it is critical to overcome the problems of narrow visible light absorption range and low carrier separation efficiency. In this work, we firstly prepared the 2D plate-like WO3/CuWO4 uniform core-shell heterojunction through in-situ synthesis method. After modification with the amorphous Co-Pi co-catalyst, the ternary uniform core-shell structure photoanode achieved a photocurrent of 1.4 mA/cm2 at 1.23 V vs. RHE, which was about 6.67 and 1.75 times higher than that of pristine WO3 and 2D uniform core-shell heterojunction, respectively. Furthermore, the onset potential of 2D WO3/CuWO4/Co-Pi core-shell heterojunction occurred a negatively shifts of about 20 mV. Experiments illuminated that the enhanced PEC performance of WO3/CuWO4/Co-Pi photoanode was attributed to the broader light absorption, reduced carrier transfer barrier and increased carrier separation efficiency. The work provides a strategy of maximizing the advantages of core-shell heterojunction and co-catalyst to achieve effective PEC performance. 相似文献
66.
《International Journal of Hydrogen Energy》2020,45(38):18946-18960
The present study reports about exploration of a multi-component photocatalytic system comprising of WO3, TiO2 and Fe2O3 with tandem n-n heterojunctions. The ternary WO3/TiO2/Fe2O3 nanocomposite with WO3 nanoparticles over the interfaces of Fe2O3 and TiO2 is synthesized by wet precipitation followed by thermal decomposition. The WO3/TiO2/Fe2O3 nanocomposite has an enhanced photocatalytic performance towards hydrogen generation by water splitting reaction under visible light irradiation, when compared to the Fe2O3/TiO2 system. A band gap of 2.10 eV, favouring visible light absorption was achieved with the distribution of WO3 nanopartcles over the interfaces of Fe2O3 and TiO2. The as prepared WTF heterojunction exhibited a maximum hydrogen production rate of 10.2 mL h−1 for a catalyst loading of 0.025 g mL−1. The enhanced photocatalytic performance is tested in presence of various sacrificial agents and proton source. In both cases, the higher photocatalytic efficiency is attributed to the more visible light harnessing ability and pronounced charge separation owing to the tandem n-n heterojunctions generated between TiO2 with WO3 and TiO2 with Fe2O3 semiconductors and enhancing the lifetime of the photogenerated electron-hole pairs. 相似文献
67.
68.
Oliver Skibitzki Yuji YamamotoMarkus Andreas Schubert Bernd Tillack 《Thin solid films》2012,520(8):3271-3275
The solid phase epitaxy (SPE) of undoped amorphous Si (a-Si) deposited on SiO2 patterned Si(001) wafers by reduced pressure chemical vapor deposition (RPCVD) using a H2-Si2H6 gas system was investigated. The SPE was performed by applying in-situ postannealing directly after deposition process. By transmission electron microscopy (TEM) and scanning electron microscopy, we studied the lateral SPE (L-SPE) length on sidewall and mask for various postannealing times, temperatures and a-Si thicknesses. We observed an increase in L-SPE growth for longer postannealing times, temperatures and larger Si thicknesses on mask. TEM defect studies revealed that by SPE crystallized epi-Si exhibits a higher defect density on the mask than at the inside of the mask window. By introducing SiO2-cap on the sample with 180 nm Si thickness following postannealing at 570 °C for 5 h, the crystallization of up to 450 nm epi-Si from a-Si is achieved. We demonstrated the possibility to use this technique for SiGe:C heterojunction bipolar transistor (HBT) base layer stack to crystallize Si-buffer layer to widen the monocrystalline region around the bipolar window and to improve base link resistivity of the HBT. 相似文献
69.
70.
Jun Wan Chenchen Pu Ruimiao Wang Enzhou Liu Xiao Du Xue Bai Jun Fan Xiaoyun Hu 《International Journal of Hydrogen Energy》2018,43(14):7007-7019
A 2D g-C3N4(pPCN)/rGO heterojunction for photocatalytic hydrogen production is fabricated by a facile dissolution strategy facilitated by H2SO4. The bulk g-C3N4 (CN) can be directly exfoliated into ultrathin protonated g-C3N4 (PCN) nanosheets under the assistance of H2SO4, and PCN can be further modified by rGO in a dissolved state under the electrostatic self-assembly process. The nanocomposite exhibits a large surface area (146.47 m2/g) and intimate contact interfaces between pPCN and rGO due to the specific synthesis method. Based on the DRS, PL and photoelectrochemical analyses, the introduction of rGO can greatly improve the light absorption and photogenerated charge carrier separation and transfer of g-C3N4. The optimal pPCN/2 wt% rGO nanocomposite shows an efficient photocatalytic H2 evolution rate of 715 μmol g?1 h?1 under visible light irradiation, which is 2.6 and 13 times higher than those obtained on pPCN and CN. In addition, a photocatalytic mechanism over a 2D pPCN/rGO heterojunction is proposed. This work offers a new effective strategy for fascinating gC3N4based nanocomposites with promising hydrogen generation. 相似文献